1. Field of the Invention
The present invention relates to a three-access polarization and frequency duplexing device.
2. Description of the Prior Art
In the field of polarization duplexers, one known type is the orthogonal-mode duplexer which has a main waveguide with a short-circuit plate placed in the axis of the main waveguide and other waveguide or so-called parallel-access waveguide at right angles to the first and placed in a critical position with respect to said short-circuit plate. This very conventional device has the disadvantage of being limited to the use of a single frequency or frequency band.
Another known type of duplexing device is described in French patent Application No. 8502209 filed on Feb. 15, 1985. In this device, a main waveguide has the function of transmitting the frequency or frequency band to be multiplexed as well as other frequency bands to two access waveguides at right angles to the main waveguide and at right angles to each other, said access waveguides being coupled to the main waveguide by means of resonant slots.
Having two outputs in different planes is often not compatible with system design requirements from a physical arrangement standpoint.
European patent Application No. EP-A-0098192 describes a multiplexing device for grouping two frequency bands, the specific application considered being a multiband antenna. Starting from the coupling access to the antenna, this device comprises in series a common circular waveguide for passing a band of high frequencies and a band of low frequencies into which open via two coupling holes relatively displaced along the common circular waveguide two waveguides at right angles to each other and constituting the accesses for the two orthogonal polarizations of the low-frequency band, a circular waveguide to circular waveguide transition, a polarization duplexer for the high-frequency band. Resonators which form a short-circuit for the frequencies of the high-frequency band are placed within the coupling holes. Looking from the coupling access to the antenna, there are placed within the common circular waveguide, between the first and the second coupling hole, a first quasi-optical filter having the function of reflecting towards the first coupling hole the waves which are located within the low-frequency band and the polarization of which is that of the wave to be passed through the first hole and, between the second coupling hole and the transition, a second quasi-optical filter having the function of reflecting towards the second coupling hole the waves which are located within the low-frequency band and the polarization of which is that of the wave to be passed through the second hole.
With respect to the aforementioned device of the prior art, the construction and application of the device in accordance with the present invention can be carried out much more simply with two low-frequency accesses and one high-frequency access and not the reverse.